This study attempts to show that an intrathoracic implanted state-of-the-art membrane oxygenator can provide physiologic levels of oxygen transfer and CO2 removal. The crux of this intrathoracic lung will be hydrosiloxane coated hollow fibers. These fibers are microporous polypropylene. These fibers result in continuous gas transfer. The investigators point out the necessary to adjust the compliance of the expansible polymeric. In an in-vitro setting the investigators will attempt to determine the ideal elasticity and to reproduce this in the implantable lung. The investigators will attempt to implant a functioning oxygenator into the hemithorax of a sheep in Phase I for a period of 6 hours. Initially the sheep will be anesthetized and then awake. Physiologic Parameters will be monitored assess the success of this device. Specific aims of this proposed Phase I of the project include finalization of design and material specification, fabrication of prototype devices, and feasibility determination by assessment of prototype performance. This includes engineering bench testing, in-vitro gas transfer and pressure/flow characterization, and in-vivo experimental animal testing. Break-through technologic advances to be incorporated into the proposed artificial lung include: utilization of a true, continuous (non-microporous), selective gas (but not liquid)-permeable polymeric hollow fiber gas transfer membrane; unique (proprietary) deployment of the hollow fibers to achieve optimum blood flow distribution with appropriate secondary flows; low resistance to blood and gas flows; low priming volume; compliance of the blood compartment to accept pulsatile blood flow from the right ventricle; surface modification to achieve maximum thromboresistance; absence of plasma leakage; and a high degree of biocompatibility. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE